The celebrity wesbite TMZ has denied accusations it had demanded co-operation from Justin Bieber in return for suppressing the video clip of him making racist jokes. The clip was published by the Sun last week, but Gawker's Defamer blog claims TMZ has been "sitting on [the video] for 3+ years" and "hold[ing] it over Bieber and his team's heads in exchange for appearances on TMZ's media properties and cooperation with stories".

TMZ has admitted suppressing the video: after obtaining the footage around 2011, "we decided not to post it", it said, "in large part because [Justin] was 15 and immediately told his friends what he did was stupid".

However, a spokesperson for TMZ has denied the accusation there was a quid pro quo for the suppression, saying Defamer's version of events is "absolutely not true".

Defamer says multiple sources "with knowledge of TMZ's editorial operations" have said the gossip website and TV show used the video as "ransom", exchanging their continued discretion for access to Bieber and his "compliance" with its stories. The day after making this agreement, Defamer's sources allege, Bieber appeared on TMZ's television broadcast. At the time, Bieber claimed his interview was pure serendipity: "my boy Harvey [Levin]", the TMZ boss, had "walked in" while the singer was dining at a nearby sushi restaurant.

On Wednesday, the New York Post reported that someone is circulating a further "15 to 20 minutes" of Bieber footage, filmed during the same period, with yet more racist remarks. In one of these clips, Bieber, who was 14 or 15 at the time, quips about "black people liking watermelon".

TMZ has been reporting on a separate plot around the Bieber clips. It claims the two videos of Bieber emerged following an extortion attempt by someone "who had worked on the star's videos". Bieber's former collaborator reportedly wanted between $500,000 (£300,000) and $1m (£600,000) to withhold the footage, in which Bieber repeatedly uses the N-word. The singer's reps are said to have declined the offer.

Bieber has already issued apologies for his behaviour in the first two videos, calling it a "childish and inexcusable mistake". "I need to step up and own what I did," he said on Wednesday. "Facing my mistakes from years ago has been one of the hardest things I've ever dealt with."